
function canvas(step) {
        var cxt_arc = wx.createCanvasContext('canvasArc');//创建并返回绘图上下文context对象。  
        cxt_arc.setLineWidth(4);
        cxt_arc.setStrokeStyle('#d7d7d7');
        cxt_arc.setLineCap('round')
        cxt_arc.beginPath();//开始一个新的路径  
        cxt_arc.arc(32, 32, 30, 0, 2 * Math.PI, false);//设置一个原点(106,106)，半径为100的圆的路径到当前路径     
        cxt_arc.stroke();//对当前路径进行描边       
        cxt_arc.setLineWidth(4);
        cxt_arc.setStrokeStyle('#e94242');
        cxt_arc.setLineCap('round')
        cxt_arc.beginPath();//开始一个新的路径 
        cxt_arc.arc(32, 32, 30, -Math.PI / 2, step * Math.PI - Math.PI / 2, false);
        cxt_arc.stroke();//对当前路径进行描边     
        cxt_arc.draw();
}


module.exports = {
        canvas: canvas
}